A frustrated science teacher, who was upset with his students for paying more attention to their cellphones than his lessons, has landed himself in hot water with the school district after he used a cellphone jammer to block their phones.

Teacher Dean Liptak faces a five-day suspension from Fivay High School in Pasco County, Florida, for using the illegal device to try to get his students to pay attention in class, according to a story by WTSP. But instead, high school administration received a visit from Verizon officials.

“Verizon had come to the school saying someone had a jamming device, because the cellphone service was being interrupted in the area,” says Pasco County School District Spokeswoman Linda Cobbe told WTSP.

The district was worried about student safety, including the possibility of an emergency 911 call needing to be made, which would have been blocked, according to WTSP’sreport.

Cellphone jammers are illegal, according to the Federal Communications Commission (FCC).